• Jonas Termansen's avatar
    Fix SEEK_END, file offset overflow, and read/write/mkpartition syscall bugs. · 568c97c7
    Jonas Termansen authored
    Fix SEEK_END seeking twice as far as requested. Centralize lseek handling in
    one place and avoid overflow bugs. Inode lseek handlers now only need to
    handle SEEK_END with offset 0. Prevent the file offset from ever going below
    zero or overflowing.
    
    Character devices are now not seekable, but lseek will pretend they are, yet
    always stay at the file offset 0. pread/pwrite on character devices will now
    ignore the file offset and call read/write.
    
    This change prevents character devices from being memory mapped, notably
    /dev/zero can no longer be memory mapped. None of the current ports seem
    to rely on this behavior and will work with just MAP_ANONYMOUS.
    
    Refactor read and write system calls to have a shared return statement for
    both seekable and non-seekable IO.
    
    Fix file offset overflow bugs in read and write system calls.
    
    Fix system calls returning EPERM instead of properly returning EBADF when
    the file has not been opened in the right mode.
    
    Truncate IO counts and total vector IO length so the IO operation does not
    do any IO beyond OFF_MAX. Truncate also total vector IO length for recvmsg
    and sendmsg. Fail with EINVAL if total vector IO length exceeds SSIZE_MAX.
    
    Don't stop early if the total IO length is zero, so zero length IO now block
    on any locks internal to the inode.
    
    Handle reads at the maximum file offset with an end of file condition and
    handle writes of at least one byte at the maximum file offset by failing
    with EFBIG.
    
    Refactor UtilMemoryBuffer to store the file size using off_t instead of
    size_t to avoid casts and keep file sizes in the off_t type. Properly
    handle errors in the code, such as failing with EROFS instead of EBADF if
    the backing memory is not writeable, and failing with EFBIG if writing
    beyond the end of the file.
    
    Fix mkpartition not rejecting invalid partition start offsets and lengths.
    Strictly enforce partition start and length checks in the partition code.
    Enforce partitions exist within regular files or block devices.
    
    Fix a few indention issues.
    568c97c7
descriptor.cpp 33 KB